Method of brazing aluminum products and furnace therefor

Abstract

When aluminium products are preheated in a preheating furnace up to about 500° C. before they are brazed with a flux in a heating furnace, a nitrogen atmosphere in the preheating furnace is made convectional by fans for improving heating efficiencies and also for having the oxygen which is brought into the preheating furnace as a disturbance thereof and scattered about in the nitrogen atmosphere, contacted to furnace inner walls of the preheating furnace which are made from carbonaceous materials, and reacted therewith so as to be changed to CO, resulting in keeping the oxygen concentration of nitrogen atmosphere low, whereby when the aluminium products are brazed by heating them in a continuous atmosphere furnace including said preheating furnace and said heating furnace, heating time thereof is shorten and the brazing is made more economically than before.

Description

FIELD OF TECHNOLOGIES [0001] This invention relates to a method for brazing various products of aluminium including aluminium alloys such as heat exchangers made from aluminium, and a continuous furnace suited for practicing such brazing method. BACKGROUND TECHNOLOGIES [0002] Brazing of aluminium products such as aluminium heat exchangers are generally performed by means of continuous atmosphere furnaces which are advantageous technologically and economically. [0003] By a mesh belt circulating through a continuous atmosphere furance, aluminium products are conveyed into the furnace, in which they successively pass through a moisture drying furnace, front chamber, preheating furnace, heating furnace, cooling chamber, and air cooling chamber, whereby the brazing completes. In the heating furnace, a solder material and flux which have been fitted in advance onto parts of the aluminium products to be brazed, are melted in order of flux first and solder next for having them brazed. [0004...

AI Technical Summary

Benefits of technology

[0014] In other words, the subject of this invention is to make a heating time shorten so that the brazing of aluminium products can be o

Problems solved by technology

However, it is not easy at all to preheat the easily oxidizable aluminium products rapidly without adversely affecting their qualities.

However, surprisingly, in the preheating furnaces for brazing aluminium products, the heating method primarily made by means of convection has not been employed.

However, when the atmosphere in the preheating furnace is agitated and heated by convection currents produced by fans, the oxygen entered into the furnace as a distrabance thereof is also stirred up and circulated in the preheating furnace, resulting in polluting its atmosphere.

Such will largely interfere with a succeeding brazing operation, even though the products are heated rapidly in the preheating furnace.

Images